This invention relates to humidifiers which utilize electrical heaters in the humidification process. More particularly, it relates to control systems for electric humidifiers.
Humidifiers are used to add moisture to the air, particularly during the heating season when heating systems greatly reduce the humidity. Various items, such as pianos, require a precisely controlled humidity in order to function properly. Piano humidifiers are commercially available from Dampp-Chaser Electronics Corporation, assignee of the present invention. Dampp-Chaser humidifiers utilize a water reservoir and a heating rod with a pair of wicking pads contacting the heating rod and the water inside the reservoir. It is desirable for the user of the humidifier to determine whether or not there is sufficient water in the reservoir and to control the humidifier heater. U.S. Pat. No. 4,150,372, issued to Allen Foote, teaches the use of a neon light to indicate the fact that the water in the reservoir is low. However, the Foote patent does not teach a technique for turning off the humidifier when the water in the reservoir is low. The present invention represents an improvement over the teachings of the Foote patent. If the heating rod continues to operate after the water reservoir is dry, or after the pads cease wicking, the air is heated by the rod without evaporating water, thereby reducing humidity, which is directly opposite to the purpose of the humidifier. Prolonged operation without water causes a drying affect, which is counterproductive and has a deleterious action. When minerals, molds and fungus collect on the pads, the pads cease wicking.